Sheet Metal Roofing
Use this CSI 3 part SimpleSpecs™ master specification to specify custom-fabricated sheet metal roofing and roofing underlayment.
Custom sheet metal roofing is fabricated from various metals including galvanized steel, pre-coated galvanized steel, aluminum-zinc alloy coated steel, pre-coated aluminum-zinc alloy coated steel, stainless steel, copper, copper-clad stainless steel, and aluminum. Other metals are also available and can be added to this section.
Roofing is installed over solid sheathing and an underlayment rather than spaced sheathing or framing. It is nearly impossible to make sheet metal roofing absolutely watertight due to its high coefficient of thermal expansion.
The advantage of rubberized asphalt underlayment is its ability to self-seal around fastener penetrations and at seams as temperatures rise. Rubberized asphalt flashings used under sheet metal is subjected to extremely high temperatures and can reach flowable consistency. A high-temperature version is available from many manufacturers.
A slip sheet is required under sheet metal to prevent adhesion and allow the metal to expand and contract.
Roofing is susceptible to waviness in the metal as the metal expands and contracts, referred to as oil canning. Oil canning is primarily an aesthetic issue and is worse on wide, flat surfaces. Placing intermediate ribs between the primary ribs minimizes oil canning, as does detailing the roofing to allow for expansion and contraction. Roofing should be allowed to move. It should not be fastened in a manner that prevents movement. Increasing the gage of the metal has little effect on oil canning.
Refer to the following for assistance in selecting and detailing sheet metal roofing:
– Architectural Sheet Metal Manual by the Sheet Metal and Air Conditioning Contractors National Association (SMACNA), available line at smacna.org,
– Technical resources by the Copper Development Association (CDA), available at copper.org,
– Roofing Manual: Metal Panel and SFP Roof Systems by the National Roofing Contractors Association (NRCA), available at nrca.net.
Related SimpleSpecs™ master specification:
The SimpleSpecs™ master specs concept
Design professionals are accustomed to seeing lengthy project specifications, so why is SimpleSpecs™ so short?
Specifications have grown evermore wordy over the years for several reasons:
The mistaken belief that specifications must be lengthy and legal-sounding to be enforceable. In fact, quite the opposite is true. Having shorter, easily understood specifications makes us less likely to have problems in the field.
A belief that having lots of words protects us from a Contactor making mistakes. There is no way to include enough statements to protect yourself from a bad contractor, regardless of the length of your specification.
Our desire to be in control of the project by specifying means and methods instead of including simple, enforceable statements.
Easier to Edit
SimpleSpecs™ is written as a series of Microsoft word files that include statements that affect construction costs or overall quality and are far simpler to edit than other master specification systems.
Each SimpleSpecs™ specification section is non-proprietary and includes three manufacturers that meet the specified reference standards, descriptive, or performance-based requirements. They are written to allow any listed manufacturers to provide the specified products.
Hidden Guide Text
Each SimpleSpecs™ specification section includes hidden text to inform and guide users in editing the specifications to suit project conditions.
SimpleSpecs™ sections are edited using pre-defined options that are contained in [brackets] or by selecting optional text separated by "OR" statements. Paragraph and page numbering are included as automatic codes, eliminating the need to renumber when revisions are made manually. Global changes to headers, footer, terms, font colors and phrases are easily updated using a third-party search and replace software, available through ZeroDocs.com.